Method of and apparatus for cutting, encasing and retrieving a core of earth formation from a well



June 4, 1963 c, DEELY 3,092,192

METHOD OF AND APPARATUS FOR CUTTING, ENCASING AND RETRIEVING A CORE OF EARTH FORMATION FROM A WELL 4 Sheets-Sheet 1 Filed Dec. 14, 1959 51715 15 17! Z L. Z7555 Y INVENTOR.

June 4, 1963 Filed Dec. 14, 1959 DEELY 3,092,192

C. METHOD OF AND APPARATUS FOR CUTTING, ENCASING AND RETRIEVING A CORE OF EARTH FORMATION FROM A WELL Q u 24 i ,30

was

x w x w I32 5 I34" Z Q B -97 E [91mm LZJZHY F{- INVENTOR.

p) Q ,l i t W Y HISHEENT June 4, 1963 c. L. DEELY 92.192

METHOD OF AND APPARATUS FOR OUT AND 3,0 TING, ENCASING RETRIEVING A E OF EARTH FORMATION F A WE Filed Dec. 14, 1959 4 Sheets-Sheet 4 LWBPJM 1.1755

INVENTOR.

HIS HEE T METHOD OF AND APPARATUS FOR CUTTING,

ENCASING AND RETRIEVING A CORE F EARTH FORMATION FROM A WELL Carroll L. Deely, 6210 North Central Expressway, Dallas, Tex. Filed Dec. 14, 1959, Ser. No. 859,216 3 Claims. (Cl. 175-253) rotary well drilling equipment to remove both hard and soft cores from the earth strata, and to encase such cores, if desired, within a shielding tubing, such as aluminium, thin plastic or the like, so the core may be transported or shipped without damage, and without having to use extreme caution in the handling thereof.

An object of this invention is to provide core retainers or catchers which are open at all times, while the core is being cut, so as to enable free entrance of the core into the inner core barrel, thereby obviating disintegration of the core.

Another object of the invention is to provide a core barrel which will remove soft cores of earth formation, which would be disintegrated by the use of conventional barrels, if the bonding strength of the elements in the formation is insuflicient to hold together to form a rigid core.

Another object of this invention is to provide a core barrel which will receive a thin metallic or plastic tubing which tubing may be removed from the core barrel without disturbing the core therein.

Still another object of this invention is to provide a core barrel wherein the core received within the core tube maybe inspected by opening the core receiving barrel longitudinally.

A further object of this invention is to provide a core barrel which is adapted to receive thin metallic or plastic tubes therein, which tubes may be removed from the core barrel without disturbing the core contained therein, and which tubes may be sealed hermetically wtih wax, plastic or the like.

-A still further object of the invention is to provide antifriotion bearings between the inner core barrel and the outer core barrel, so as to lessen the friction and to insure alignment therebetween, thereby assuring accurate cutting of the core.

Yet another object of the invention is to provide a positive core gripping mechanism, so that the core catcher will accurately and securely grip the core, and to provide means for determining, from the surface, when the core catcher has moved into position to engage the core.

Still another object of the invention is to provide a core barrel whereby a drop plug may be inserted into the drill stem, which drop plug will cause engagement of the core gripping means with the core, to enable the core to be broken off at the bottom of the well, without shutting ofi circulation of the drilling fluid.

Yet another object of the invention is to provide a core barrel which is accurate to use, positive in obtaining a. core, and which may be used in any type formation.

A still further object of this invention is to provide a drop plug which may be selectively directed into a drilling fluid conduit which is under pressure, while the drilling United States Patent 0 "ice fluid is flowing therethrough and without the loss of pressure or of fluid.

Yet a further object of the invention is to provide a drop plug for a string of drill pipe, which drop plug may be directed into the string of drill pipe for performing a mechanical operation therein without having to shut off the pump pressure or to lift the drilling bit off the bottom of the well.

With these objects in mind and others which will become manifest as the description proceeds, reference is to be had to the accompanying drawings, in which like reference characters designate like parts in the several views thereof, in which:

FIG. 11 is a diagrammatic elevational view of a drilling rig, including a rotary table and a mud pump, and showing a longitudinal section through a portion of a well with a string of drill stem therein, with a core barrel shown on the lower end of the drill stem, with parts being broken away and shortened to bring out the details of construction;

FIG. 2 is an enlarged perspective view of one form of core catcher used with the core barrel;

FIG. 3 is a perspective, exploded view of a core receiving tube, with parts broken away and shortened, and

' showing insert core receiving containers for use within the core receiving tube;

FIG. 4 is an elevational view of a core receiving tube and showing a core therein, with sealing media, such as sealing wax, paraflin or plastic, covering each end of the core receiving tube and surrounding the core intermediate the tube and the core to form a support therefor;

FIG. 5 is a longitudinal, sectional view through one form of core barrel, with parts broken away and shortened FIG. 5, looking in the direction indicated by the arrows;

FIG. 10 is a longitudinal, sectional view through a portion of the drill stem, which has a plug release mechanism built therein, and showing a plug secured in the drill stem by the release mechanism;

FIG. 11 is an enlarged, longitudinal, sectional view,

taken on the line 1111 of FIG. 10, and showing the plug and the plug release mechanism, as shown in FIG. .10;

FIG. 12 is a fragmentary, longitudinal, sectional view of the lower portion of the core barrel, showing a modi- 'fied core breaking and retaining mechanism thereon;

FIG. 13 is a fragmentary sectional view taken on the line 13-13 of FIG. 12, looking in the direction indicated by the arrows, and showing, in dashed outline, the core catching fingers in closed position;

FIG. 14 is a sectional view taken on the line 14-14 of FIG. 12, looking in the direction indicated by the arrows;

FIG. 15 is an elevational view of the drop plug shown in FIGS. 10 and 11, showing the drop plug apart from the device;

FIG. 16 is an enlarged, fragmentary, elevational sectional view of the lower end of the inner core barrel, showing a core gripping and breaking cam fitted therein for breaking 01f hard cores;

FIG. 17 is an enlarged, fragmentary, elevational, sectional view of the lower portion of the core barrel, showing a core gripping catcher therein, as shown in FIG. 2,

a and showing a releasable latch mechanism for holding the core gripping catcher in expanded condition;

FIG. 18 is a view similar to PEG. 17, but showing the core breaker fingers in place to break and catch soft cores, the retracted position being shown in full outline, with the breaking position being shown in dashed outline;

FIG. 19- is a fragmentary sectional view through the lower portion of a core barrel, showing anti-friction rollers fitted between the inner and outer core barrelsto guide the inner core barrel in concentric relation with respect to the outer core barrel;

FIG. 20 is a sectional view taken on the line 20-20 of FIG. 19, looking in the direction indicated by the arthe inner and outer core barrel and the roller retainer being shown in cross section.

With more detailed reference to the drawings, the numeral 1 designates generally a rotary table of a rotary drilling rig. A pump 2 is provided for pumping drilling fluid, and is shown supported in position to withdraw the drilling fluid from the slush pit 4 through suction line 6,

and which drilling fluid is discharged through conduit 8 and swivel 10 into drill stem 12. A drill stem sub 14 is provided in the length of drill stem 12 above the Kelly joint 16, which sub'has an angular connection 18, as will best be seen in FIG. 10, to receive a releasable drop plug into the Kelly joint 16 and drill stem 12. The angular connection 18 is so constructed that the drop plug 20 may be retained in the bore 22 of the angular connection 18, while the drilling fluid is being circulated through the drill stem under pressure, and a screw threaded plug 24 is designed to complementally engage the upper end of the screw threaded angular connection 18 in fluid tight relation, which screw threaded plug 24 has a shoulder 40 thereon, which shoulder retains the drop plug 20 against movement into the sub 14 and drill stem 12 until it is desired to release the drop plug 20. The screw threaded plug 24 has. sealing gaskets or O-rings 26 at the lower end thereof to form a fluid tight seal with the inher bore of angular connection 18, which sealing elements or O-rings permit rotary and longitudinal movement ofscrew threaded plug 24 within angular connection 18. The screw threaded plug 24 has an axial bore therein, which bore is screw threaded for at least a portion of the length thereof tothreadably receive a screw core being cut. The outer core barrel 44 comprises tubular sections 48, 50, 52 and 54, which are screw threaded together in end to end relation, with the core bit 56 being screw threaded onto the lower end thereof, which core bit 56 is usually a diamond set bit with an axial opening therein so as to cut an 'annular land from the earth formation, to leave an upstanding core extending upward into the inner core barrel 46,.

The inner core barrel or inner tubular member 46 comprises tubular sections 62, 64, 66, 68, 70, 72 and 74, which are screw threaded together in end to end relation. The upper end of the upper tubular section62 of the inner core barrel 46 is reduced in diameter to complementally fit into the counterbore 85 formed in the lower end of upper section 48 of the outer core barrel 44. Shouldered recesses 84 are formed within the bore of the upper section 48 of the outer core barrel 44, a spaced distance up from the lower end thereof, and shouldered recesses84a 'are formed intermediate the shouldered recesses 84 and the lower end of the upper section 48 of the outer core barrel 44, which recesses receive the lower end of latch dogs 78, as will be brought out more in detail hereinafter.

The inner core barrel 46 is attachably connected to the upper section 48 of the outer core barrel 44 by means of latch dogs 78, which latch dogs are circumferentially spaced'around the bore 80 of the upper section 62' of the inner tubular core barrel 46, in close prom'mity to the constricted opening in the bore 80 formed by annular shoulder 76. The latch dogs 78 are pivotally mounted on the respective pivot pins 82, which pins pass chordally through the inner core barrel 46 near the upper end thereof, so the upper end of each dog, which upper ends are each inwardly and downwardly tapered, will swing inward into axial opening 80, under the influence of springs 81, which springs each have one end thereof in engagement with the respective lower portion of latch dogs 78 curved slot 32 formed therein, in which slot is a spring pressed bolt 34, which spring pressed bolt 34 engages slot 32 to hold the screw threaded element 28 against rotation, when in one position. A tool 36 is provided'to release the spring pressed bolt '43 to enable the turning of the screw threaded element 28, which element may be turned sufliciently to allow the shoulder 38 on drop plug 20 to disengage shoulder 40 on one side of bore 42 of the screw threaded plug 24. In this manner the drop plug 20 may be released into the string of drill stem 12 through which fluid is being circulated at high pressure, but will not permit the escape of fluid from the drill stem out through angular connection 18, as will be more fully brought out hereinafter.

The core barrel, which is designated generally by the numeral 43, comprises two general asesmblies, namely,

'core bit 56 on the lower end thereof, and an inner tubular member or inner core barrel 46, which receives the and the other end of each spring is in engagement with an abridging segment of the upper section 62 of the inner tubular member 46.

When the latch dogs 78 are positioned as shown in full outline in FIGS. 5 and 6, the lower ends thereof engage shouldered recesses 84, which are formed in tubular section 48 of the outer core barrel 44, to hold the inner core barrel 46 against downward movement relative to the outer core barrel 44, and will hold the upper face 88a of the inner core barrel 46 in seated, sealing relation against the face 88 of the outer core barrel 44, which.

faces 88 and 88a form a fluid tight joint between these elements 44 and 46.

The lower end of each latch dog78, when in the po-' tubular sections 62 and 64 on a stem 104, which stem is mounted in bearings 106 and 108. The respective bearings 106 and 108 are mounted below and above shoulder 110 in tubular section 64 of the inner core barrel 46, so as to journal the stem 104 of the tubular section 66 of the inner core barrel, so the upper section 62 of the inner core barrel, which has latch dogs 78 pivoted thereto so the lower ends of the latch dogs will engage recesses 86 to support the inner core barrel 46 within the outer core barrel so the, outer core barrel 44 may be rotated relative thereto, while the inner core barrel 46 below tubular section 64 remains non-rotatable with respect to the core therein. The chamber 112, which houses bearings 106 and 108, is filled with lubricant,

therein by a lipped, annular alastomer seal 116, which is fitted in the lower end of tubular section '64 of the inner core barrel 46.

As the core bit 56 cuts into the earth strata, the inner core barrel 46 moves downward over :the core being cut, which core moves freely into the inner core barrel 46 without engagement of the core grippers or the core breakers on the formation of the core while it is being cut, thereby abrading and disintegrating the core as it is being cut, is prevented. A thin metallic or plastic tubing may be fitted within tubular sections 68, 70 and 72 of the inner core barrel, thereby, the core, as it is being cut, is encased within tubing 122, until the desired number of feet of formation is cored.

As the core bar-rel moves downward over the core, the drilling fluid, gas or the like, is expelled from the upper end of the core barrel through valved, axial opening 124 in the lower end of tubular section 66 of the inner core barrel, and the fluid is prevented from reentering opening 124 by a check valve 126. As the drilling fluid moves upward into opening 128, the tubular section 66 of the inner core barrel, it is vented out through lateral opening 139 near the upper end of section 66, to the exterior thereof.

The tubular section 70, of the inner core barrel 46', is made of a pair of semi-cylindrical, longitudinal portions, which, when placed together, may be selectively locked by pairs of J-hooks 132 and J-slots 134-, which are provided on the complementary portions, to form a composite tubular member 7 0. When these portions are complementally fitted together, the threads at each end of the respective semi-cylindrical portions will be in register, so that the upper end of the member 70 may be screwed into tubular section 68 of the inner core barrel 46 and the lower end thereof may be screwed into tubular section 72 of the inner core barrel. However, when thecore has been cut, the inner core barrel 46 may be removed from the outer core barrel, as will be more fully brought out hereinafter.

When the desired length of core has been cut and it is desired to recover this core, the drop plug 20 is released from angle connection 18 of drill stem 12 into the drilling stream, while drilling fluid is flowing downward therethrough and through Kelly joint 16, by turning screw threaded plug 28 within angular connection 18, which turning movement is accomplished by means of a tool 36. Upon turning screw threaded plug 28, the drop plug 20, having shoulder 38 thereon, will be moved laterally, so that the shoulder 38 thereof will become disengaged from shoulder 40 on screw threaded plug 24. The downward movement of drop plug 20 will continue into the upper end or core barrel 43 and will substantially close the constricted opening 87 of bore 86, with the lower tapered end of drop plug 21 engaging the bevel 'faces of latch dogs 78 which are pivotally mounted on pivot pins 82, which pins pass chordal- 1y through the upper end of section 62 of inner core barrel 46.

With the constricted opening 87 in outer core barrel 44 closed, the passage of drilling fluid will be momentarily interrupted, whereupon, the pressure gauge 3 will indicate a rise in pressure. However, upon increase in pressure on drop plug 20, the wedging action of the lower tapered end thereof will cause latch dog 78 to pivot about pivot pins 82 to move the upper ends of the latch dogs 78 into recesses 83 inthe upper portion of section 62 of the inner core barrel 46, which will cause the lower portion of the latch dogs 78 to move inward against the pressure of spring 81 until the lower ends of latch dogs 78 become disengaged from the shoulders 84 of recesses 83. Whereupon, the drop plug 20 will move downward to the position indicated in dashed outline in FIG. 5, to seatupon constricted annular shouldered portion 76 of bore 80, upon continued application of drilling fluid pressure on the plug 20, the inner core barrels 46 will 6 move downward relative to the outer core barrel 44-, which in turn, will move the lower tapered end of core gripper retainer latch into engagement with the bevel face 92 within the bore of core bit 56, whereupon, on continued downward movement of core gripper retainer latch 99, with respect to the bevel face 92, the latch will be caused to pivot about pin 91, which passes chordally through the lower section 74- of the inner core barrel 46 to cause the upper end of the latch 99 to move from between an end of the resilient core gripper ring 96 and an abutment 94 formed thereon, which latch holds the resilient core gripper ring 96 in expanded condition, which latch will permit the gripper ring 96 to spring inward into gripping relation with the core which has been cut. The resilient core gripper ring 96 is tapered inwardly and downwardly, and has circumferentially spaced, longitudi nally formed ribs on the outer surface thereof to permit ready resilient expansion and contraction of the core gripper ring 96. The ring 96 complementally seats in a tapered seat within inner core barrel 46 near the lower end thereof, which, upon upward movement of the inner core barrel 46, causes wedging engagement between the gripper ring and the core being cut. The resilient core gripper ring 96 is substantially annular in shape and has the edges thereof over-lapping so as to form a structure that is generally known as being complementally stepcut, in the art rings, whereby the edges over-lap in such manner that when the resilient core gripper ring is in contracted position the inner surface will present a substantially cylindrical bore and the outer tapered surface present a substantially smooth surface where the exterior edge which forms one of the abutments 94 and the abutment 94 of the adjacent rib abut, however, when the resilient core gripper ring is in expanded condition the latch 98 will be received between abutments 94 on the outer periphery thereof.

Substantially simultaneously with the gripper ring 96 springing inward to grip the core, cam faces of corebreak-off dogs 97 will engage tapered cam face 92 in the upper end of the bore of core bit 56, which will cause break-off dogs 97 to be revolved through approximately 45 degrees about pin 97a, which pin passes chordally through the lower section 7 1 of the inner core barrel 46 and through break-01f dogs 97, against tension of torsion springs 102, which springs interengage between break-0E dogs 97 and the lower section 74 of inner core barrel 46. Then by exerting pressure on the fluid in the drill stern, and by pulling upward on the outer core barrel 44-, the break-off dogs 97 will move from the position as shown in full outline in FIG. 5 to that shown in dashed outline in FIGS. 9 and 18, if the formation is sufiiciently soft for such action to occur, thereby break-off dogs 97 will sever the core, which has been cut, at a point near the lower end thereof. It is preferable to have four of these dogs 97, so the greater portion of the area of bore 98, of the inner core barrel 46, will be closed when the dogs are in the position shown in dashed outline in FIGS. 9, l3 and 18, thereby giving complete support to the core therein, even though the formation which makes up the core does not have sufiicient bonding strength to be selfsupporting, thereby enabling substantially full core recovery.

Upon movement of the inner core barrel 46 downward relative to outer core barrel 44 the passages 118, which passages are formed in the periphery of the reduced portion 85 of the upper section 62 of inner tubular member 46, are opened, so as to permit the flow of drilling fluid therethrough and into an annular space intermediate the inner core barrel 46 and the outer core barrel 44. The drilling fluid will flow downward therein and out through the opening in the lower end of drill bit 56, and upward through the annulus formed between the outside of outer core barrel 44 and the wall of the well. Upon movement of inner core barrel 46 downward, which will open passages 118, a drop in drilling fluid pressure will occur, and be indicated by pressure gauge 3, which will indicate that the function of releasing the dogs 78, on the upper end of inner core vbarrel 46 from engagement with the shouldered portion 84- of outer core barrel 44, has been accomplished and that the inner core barrel 46 has moved downward relative to the core barrel 44,

In order to recover the core from the well, a pull is exerted on drill stem 12, which will cause the core gripper ring 96, which is tapered inwardly and downwardly on'the outer periphery thereof, to move relative to the tapered seat within lower section 74 of the inner core barrel 46.v As the core barrel 43 moves upward, the break-off dogs 97, if they have not revolved through the maximum arc of revolution about pivot pins 97a, willcontinue to move until the core is severed, if such action does not take place by the initial downward movement of core barrel 46. With the core severed, the drill stem 12 is moved until the upper section 50 of outer core barrel 44 is gripped within slips S, which slips are positioned within rotary table 1. The drop plug 29 may be moved from axial bore 80 in the upper portion 62 of inner core barrel 46 by engaging a'removing tool with the shouldered portion 38 of drop plug 20, which enables drop plug 20 to be moved upward through constriction 87 and out through axial bore 36. With section 48 of the outer core barrel 44 extending above the slips S, and with the slips engaging the tubular section 50 to prevent downward movement thereof, and with the latch dogs 78 engaged within the recesses 84a in the lower end of upper section 48 of outer core barrel 44, the sections '48 and 50 are in position to be separated.

The upper section 48 of the outer core barrel is then unscrewed from the upper end of section 59 of the outer core barrel 44, and the upper section '48 lifted upward, as by suitable hoist means, such as a hoist line connected thereto, which will lift the inner core barrel 46 upward out of outer core barrel 44, and since the inner core "barrel often attains, a length of 50 or more, the inner core barrel is then placed in a horizontal position on a suitable plane surface and the section 70 disengaged from the sections 68 and 72 by nnscrewina By relative longitudinal movement of one portion of tubular member 70 with respect to the complementary portion thereof, the tubular member 70 may be divided longitudinally, to enable the removal laterally of the tubing 122 containingthe core, if the tubing 122 is used, or the core itself may be removed laterally. The removal of the core C from the tubular member is a simple operation, which does not require driving the core out of the tubular member longitudinally, as has been the usual practice heretofore. Therefore, cores may be removed from tubular member 70, even though the formation which makes up the core does not possess sufficient bonding strength to be self supporting, and the material cored will be in the same sequence within the member 70, as it was cut from the formation. 1f tubing I122 is utilized within the core barrel, it may be used in lengths to provide convenient sections for handling and packing, and even though the core C does not completely fill the inner tubing 122, as shown in FIG. 4, wax, paraflin, plastic or the like, may be poured into the annulus between the core C and tubing 122, and the ends of the tubing sealed with wax, paraffin, or plastic, which will maintain the core C in preserved condition for shipment, or for future use. It is preferable to use aluminum or plastic tubing 1220f relatively thin gauge, so that the tubing may be readily removed from the core in the laboratory, by cutting the tubing longitudinally, so as not to disturb the relation of the core to the strata from which it was cut. If plastic tubing is used, this may be transparent, so the core may be inspected while encased within the tubing.

Various formations require different treatment for Ohtaining maximum core recovery. For relatively hard formations, into which core break-off dogs 97 will not readily 8 penetrate, it is preferable to have eccentrically mounted break-off dogs 97. The dogs each has a contoured are mounted in a manner similar to the mounting of the break-off dogs 97. 'The dogs each has a contoured face to grip the core upon engagament of outstanding cam ends 152 on dogs 150 with the bevel face 92 on core bit 56, whereupon, the eccentrically mounted dogs 150 will roll about the respective axes of pins 154, approximately 90 degrees, against the tension of the re spective torsion springs 156, which action will 'cut into the core to cause breakage thereof at this point. There are preferably four of these eccentrically mounted dogs 159 on the lower end of tubular member 74 Dogs 97, FIGS. 12 and 19, have the axes thereof mounted in a plane a spaced distance upward from dogs 150, so in event the dogs 150 crush the core C, the tubular section 74 is moved relative to bit 56, which permits the cam faces or shoulders 95, of the dogs 97, to engage the bevel face 92 within the bore of bit 56, which will cause the dogs 97 to be moved through an angle of approximately 45 degrees. Upon exerting an upward pull on core barrel 43, the outer tubular portion 44 will move upwardly, whereupon the cam faces. 95 bear upon bevel face 92 of the bit 56 to move the dogs 97 into the position shown in dashed outline in FIG- 18, so as to substantially close the axial bore therein below the core C, to sever the core, and whereby the core is supported to enable the recovery thereof.

The tubular member 70, as shown in FIG. 12, is of substantially the same construction as the form shown in FIG. 5, however, the tubular member as shown'in FIG. 12, is shown without the thin metal or plastic tubing 122 therein, as such tubing is not required for hard 7 cores, which are completely self-supporting, unless fluids are present and it is desired to retain such fluids, in which event, the metal or plastic tubing 122 maybe used and the ends thereof sealed with wax, paraflin, plastic or the like, and whereby any voids between the tubing and the core may be filled with wax, plastic or the like within the length of tubing 122, to support the core therein. In this manner fluids are not allowed to escape from the core, and the core is supported against damage which may be inflicted by handling or shipping.

In'cutting hard formations, it is often desirable to maintain the outer core barrel 44 in precise aligned relation with respect to the axis of the inner core barrel 46, therefore, a roller bearing, designated generally at 170, may be positioned around the lower end of the inner core barrel 46 and within the outer core barrel 44, so that the rollers 172 will maintain the inner core barrel 46 and the outer core barrel 44 in coaxial relation.

Roller bearing is so constructed that the retainer members 174 are placed around tubular member 72 of the inner core barrel 46, to surround annular groove 176.

Rollers 172, which have holes therein, are then aligned with apertures within retainers 174, and pins 178 are positioned through the respective apertures of said retainers and said rollers, which arrangement will retain the rollers 172 within annular groove .176, against relative longitudinal movement on tubular member 72. The outer, diameter of roller bearing 170 is in bearing relation with the inner diameter of the outer tubular member 54. It is preferable to have rollers 17-2 of the roller bearing made of wear resistant material, which does not require lubrication, such as plastic, which is known to the trade as Teflon, or the like.

Operation In taking cores from the earth strata, such cores often exceed 50 feet in length, and it is desirable to retain the corecatchers or grippersout of engagement with the core until the entire length of the core is cut, and also to .maintain the inner core barrel non-rotatable with respect to the core being cut, and while it is desirable to wash the abraded particles of loose formation awayfrom the core being cut, before it goes into the inner core barrel,

9 it is also desirable to protect the core being cut from the circulating fluid, after the loose cuttings have been washed from the face of the core.

Normally the drilling fluid from the slush pit 4 is drawn upward through suction pipe 6 into pump 2 and discharged out through hose 8 into swivel 10 and thence through drill stem 12 and Kelly joint 16 into axial opening 86 of core barrel 43, thence into axial opening 80 in section 62 of the inner core barrel 46, whereupon, the fluid passes through constricted opening formed by shoulder 76 within the upper portion 62 of the inner core barrel near the upper end thereof, and out through angular passages 63 formed in the upper portion 62 of the inner core barrel into an annular passage 120, which passage is exterior of the inner tubular member 46 and within outer tubular member 44, with the fluid passing downward between the lower end of tubular section 74 and out through the annulus formed by the outer diameter of the core being cut and the axial opening in hit 56. The abrading elements on bit 56, together with the fluid passages formed within the core bit, permits the fluid to pass outward to a point exterior of the bit 56 and upward exterior of the outer core barrel 44 to the mouth of the bore hole.

After the desired depth of strata has been cut by the bit 56, which cuts an annulus around the core to be retrieved, and it is desired to retrieve the core, the drop plug 20, which is maintained under pressure in the drilling fluid within bore 22 of angular connection 18, may be released without shutting down the pump, by turning screw threaded element 28 through approximately 180 degrees, by utilizing tool 36, which tool is used to depress spring pressed plunger 34 which engages slot 32. Whereupon, the tool is moved from angular position as shown in FIG. 11, to a position which is substantially axial with threaded element 28. Upon turning the screw threaded element 28 through approximately 180 degrees, the eccentrically mounted dog point 29, of screw threaded element 28, which dog point 29 is engaged within the axial bore within the upper end of drop plug 20, which dog point will move shoulders 38 on drop plug 20 out of engagement with shoulder 40 on the angular connection 18, upon rotation of threaded element 28, and the drop plug 20 will move out of angular connection 18 into the axial passage of sub 14 and thence into the axial opening of Kelly joint 16, thence down through drill stem 12 into core barrel 43. Whereupon, the lower tapered portion of drop plug 20 will come into engagement with the upper ends of dogs 78 to move the lower ends of the dogs 78 out of engagement with the shoulders of recesses 84, thereby the plug 20 will form a seal with the constricted opening formed by annular shoulder 76 in the upper end portion of inner tubular member 46.

Upon application of fluid pressure, by pump 2, to the drilling fluid in drill stem 12, a rise in the pressure will be noted on pressure gauge 3, on the discharge side of pump 2, which rise in pressure will indicate that the plug 20 has seated in the constricted opening formed by annular shoulder 76 within the upper portion 62 of the inner core barrel near the upper end thereof. However, if the plug continues to close the opening, a rise in pressure will be noted on pressure gauge 3, which will indicate that the inner core barrel has not moved relative to the outer core barrel, which will indicate that the core gripper elements have not gripped the core. However, if the pressure drops it will indicate that circulation is being had downward through the core barrel, whereupon the inner tubular core barrel 46 will be moved downward, which will cause the circulation of drilling fluid to pass between face 88a on the upper end of inner core barrel 46 and the lower shouldered face 88 in tubular section 48 of the outer core barrel 44. The drilling fluid will then pass downward through passage 118 into annular opening 120 and out through the annular opening between the outside of the core being cut and the inner diameter of core bit 56.

As an alternate method of maintaining circulation, while the core is being broken off, a tension may be applied to drill stem 12 in such manner as to lift the outer core barrel 44 a short distance, usually about one inch, while the plug 20 is in place, whereupon, the shouldered face 88 on the outer tubular member 48 will move upward away from face 88a on the upper end of inner core barrel 46, whereupon, the circulation of the drilling fluid is diverted from axial bore 86 between faces 88 and 88a into passage 118, to accomplish the same result.

Upon relative movement between the inner core barrel 46 and the outer core barrel 44, the core gripper ring 96 and core break-off dogs 97 will move into engagement with the core to sever the core and to maintain the core against downward movement relative to the inner core barrel, to enable the removal thereof from the bore hole of the well, in the form of invention as shown in FIGS. 2, 5 through 9, 17 and 18.

In the form of the invention as shown in FIGS. 12, 16 and 19 second core engaging break-off dogs 150, which are eccentrically mounted, are similar to breakofi dogs 97 in their manner of operation, except the mechanical power of the eccentrics which engage the core, gives greater crushing action and are usable in severing cores from particularly hard formation. The core barrel 43 is removed from the bore hole and disassembled, when this form of core break-01f dogs are used, in the same manner as in the form of invention as set out above for FIGS. 5 through 9.

Having thus clearly shown and described the invention, what is claimed as new and desired to be secured by Letters Patent is:

'1. A core gripping means for use in a core barrel, which core gripping means comprises; an annular member, the inner diameter of which annular member is uniformly cylindrical throughout the length thereof, the outer portion of which annular member is frustro-conical in shape, longitudinal ribs formed on the outer surface of said annular member, which ribs form longitudinal grooves on the outer surface of said annular member, said annular member being split longitudinally with the edges thereof being step-cut and over-lapping, said annular member being made of a resilient material, a movable abutment mounted on the core barrel and being positioned between one of the edges of said annular member and one of said longitudinal ribs to selectively maintain said annular member in expanded condition.

2. A core barrel for use in a bore hole in earth formation to cut a core therefrom, in combination with an outer tubular member, an inner tubular member mounted within said outer tubular member for relative rotation of the outer tubular member with respect thereto and for limited longitudinal movement of said inner tubular member with respect to said outer tubular member, a latch member pivotally mounted near the upper end of said inner tubular member and being engageable with the outer tubular member to selectively hold said inner tubular member against relative downward movement, a cutter means mounted on the lower end of said outer tubular member, which cutter means is adapted to cut an annular land in said earth formation, a substantially annular, resilient core gripping means mounted in said inner tubular member and being coaxial therewith, said annular, resilient core gripping means being split longitudinally and forming abutments near each edge thereof, said annular, resilient core gripping means being tapered inwardly and downwardly on the outer side thereof, said inner tubular member having the lower end thereof tapered inwardly and downwardly to receive complementally said annular, resilient core gripping means, further latch means mounted on said inner tubuible from theupp'erend of said bore hole to selectively release said latch near the upper end of said inner core barrel from engagement with said outer core barrel to enable said inner core barrel to move downward by fluid pressure to move said further latch out of engagement ,with the abutments on said annular, resilient core gripping means to permit binding engagement of said core gripping'means with the core of earth formation being cut; 7 Y

B. A core gripping device for use with a core barrel, as defined in claim 2; wherein means within the bore of said outer core barrel is engageablewith said inner core barrel to move said inner core barrel downward,

and wedge means on said outer core barrel, which wedge means is 'complementally engageable with said movable abutment mounted on said inner core barrel to move said'abutment out of engagement'with said annular memher to enable the annular member to move into a contracted position.

, References Cited in the file of this patent UNITED-STATES PATENTS Bullock May 8, 1900 Bashara Dec. 18, '1923 Bower Sept. 28, 1926 Bower Sept. 28, 1926 Dodds Oct. 29, 1935 Howard et al. Q. Apr. 28, 1936 Catland :Nov. 30, 1937 Humason et a1. Aug. 9, '1938 Baker Nov. 12, 1940 Howard et a1. Feb. 4, 1941 Appleby Mar. 2, 1943 Grable -2 Sept. 12, 1950 Havlick Dec. 5, 1950 Schnitter Dec. 29, 1953 Baker July 26, 1955 

1. A CORE GRIPPING MEANS FOR USE IN A CORE BARREL, WHICH CORE GRIPPING MEANS COMPRISES; AN ANNULAR MEMBER, THE INNER DIAMETER OF WHICH ANNULAR MEMBER IS UNIFORMLY CYLINDRICAL THROUGHOUT THE LENGTH THEREOF, THE OUTER PORTION OF WHICH ANNULAR MEMBER IS FRUSTRO-CONICAL IN SHAPE, LONGITUDINAL RIBS FORMED ON THE OUTER SURFACE OF SAID ANNULAR MEMBER, WHICH RIBS FORM LONGITUDINAL GROOVES ON THE OUTER SURFACE OF SAID ANNULAR MEMBER, SAID ANNULAR MEMBER BEING SPLIT LONGITUDINALLY WITH THE EDGES THEREOF BEING STEP-CUT AND OVER-LAPPING, SAID ANNULAR MEMBER BEING MADE OF A RESILIENT MATERIAL, A MOVABLE ABUTMENT MOUNTED ON THE CORE BARREL AND BEING POSITIONED BETWEEN ONE OF THE EDGES OF SAID ANNULAR MEMBER AND ONE OF SAID LOGITUDINAL RIBS TO SELECTIVELY MAINTAIN SAID ANNULAR MEMBER IN EXPANDED CONDITION. 